AVS 47th International Symposium
    Semiconductors Thursday Sessions
       Session SC+SS+EL-ThA

Paper SC+SS+EL-ThA9
Structure and Optical Properties of ScN(001) Grown by Molecular Beam Epitaxy

Thursday, October 5, 2000, 4:40 pm, Room 306

Session: III-Nitride Growth and Nucleation
Presenter: H. Al-Brithen, Ohio University
Authors: H. Al-Brithen, Ohio University
A.R. Smith, Ohio University
W.M. Jadwisienczak, Ohio University
H.J. Lozykowski, Ohio University
Correspondent: Click to Email
Scandium nitride is grown by molecular beam epitaxy on MgO(001) substrates. Reflection high energy electron diffraction and x-ray diffraction both confirm the (001)-orientation of the ScN layer. The measured lattice constant is in close agreement with the expected lattice constant a = 4.501 Å, and there is no sign of strain aside from that due to differential thermal contraction between film and substrate during cooling. As measured by atomic force microscopy and scanning tunneling microscopy (STM), these films are found to be smooth, with terraces separated by steps of height a/2. As the Sc flux is varied, the growth morphology also varies - from that of plateaus and pyramids (for lower Sc flux) to that of spiral mounds (for higher Sc flux). We associate the transition with a particular ratio of Sc flux to N flux. Films grown with a lower Sc/N flux ratio have a distinct reddish appearance, and a turn-on feature at 570 nm in the cathodoluminescence (CL) spectrum is measured, consistent with a band gap energy of about 2.2 eV. Films grown with higher Sc/N flux ratio are dark in appearance, and no turn-on feature at 570 nm is observed in the CL spectrum. STM images atomically resolve the rock-salt surface lattice for films grown with lower Sc/N flux ratios; however, for films of higher Sc/N flux ratio, small protrusions are observed on the terraces, which are most likely excess Sc atoms. The effect of the Sc/N flux ratio on the stoichiometry of the films will also be discussed.